The present invention relates to an electron beam microanalyzer having improved analytic performance and simplified structure compared with the most relevant prior art.
Conventionally, as shown in FIG. 2A, an optical reflecting mirror 212 and an optical objective lens 213 are arranged within an objective lens 211 provided in an electron beam irradiation system having a vertical optical axis. At the center of the optical objective lens 213, there is provided a capillary 214 for preventing glass from taking a charge due to the electron beam. An incident light 215 emitted from a light source passes through a semireflecting mirror 216, and then is deflected by 90.degree. by the optical reflecting mirror 212 to irradiate, through the optical objective lens 213, a surface of an object 217 to be measured.
Simultaneously, an optical system is mechanically adjusted to so that the irradiated point on the surface of measured object 217 is disposed at the center of an optical image. In this example, alignment of the electron beam axis and the optical axis requires mechanical adjustment, which is troublesome. Since a hole is provided in optical lens 213, the brightness of an image of a sample is low and resolution is deteriorated. Lack of uniformity in brightness of the image and viewing defects occur at low magnification. Further, the conventional device has a complicated structure, is troublesome to install, and is costly.
When an electron beam irradiation system and an optical microscope have their axes oriented vertically to a sample and offset laterally from one another, as shown in FIG. 2B, it is impossible to observe the electron beam axis and the optical axis simultaneously, therefore confirming alignment of the two axes is difficult. Further, the conventional device requires good movement resolution of a stage which can move with a sample loaded thereon in a sample chamber, and also needs to store the image obtained by the optical microscope, which results in high cost.
In the conventional device, when either the electron beam irradiation system or the optical microscope is simply obliquely incident on the sample, if a surface of the sample is uneven or the operation distance changes, the electron beam axis and the optical axis do not coincide on the surface of the measured subject 17 as shown in FIG. 2C. Therefore, the shape and size of a sample which can be observed are limited and the device can not be used as a general purpose device.
Such a conventional electron beam microanalyzer has problems due to the complicated structure mentioned above, deterioration in resolution, viewing defects and high cost.